Oscar fredkik jonssox



(No Model.)

0. F. JONSSON.

AUTOMATIC STOP APPARATUS FOR MOTORS DRIVING DYNAMO ELEGTRIGMAOHINES.

No. 326,223. Patented Sept. 15, 1885.

fig 1 W UNITED STATES PATENT OFFICE.

OSCAR FREDRIK JONSSON, OF STOGKHOLM, SYVEDEN.

AUTOMATIC STOP APPARATUS FOR MOTORS DRIVING DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 326,223, dated September 15, 1885,

(No model.)

To all whom it may concern.-

Be it known that 1, Oscnn FREDRIK JonssoN, a subject of the King of Sweden, residing at Stockholm, Sweden, haveinvented certain new and useful Automatic Stop Appa ratus for Motors Driving Dynamo-Electric Machines,of which the following is a specification.

The object of this invention is an automatic stop apparatus to be interposed in the circuit ofa dynamomachine, near the motor, to prevent the destruction of the dynamo-machine when interruptions or short-circuitings occur by instantly stopping the motor.

The apparatus is represented in the annexed drawing, which shows a side view of the stop apparatus.

The apparatus is interposed in the circuit ofthe dynamo-machine by connecting its polescrews A and B in the main circuit. At the pole-screw A the current divides and passes simultaneously through two electro-magncts, O and D, and joins again at E, and the whole passes through the insulated strips F and G and to the pole-screw B. The circuit between the strips F and G is completed by each strip having on its end a piece, H, descending into a vessel, I, containing mercury. The vessel I is mounted on the top of a vertical bar, K. This bar passes through and is guided by two cars, L, and is at its lower end provided with a plate, M, the edge of which comes against a screw-head, N, on the armature O of the elec tro-magnet D. This armature is held back by a spring, P, from the magnet, the spring being sufliciently strong to overpower the attraction until the current has increased to such a degree that danger is imminent both to the dynamo-machine and the circuits. The armature of the electro-magnet 0 consists of a doublearmed lever, Q, provided with metal screws R in front of the poles of the electro magnet,i.n order to diminish the effect of the residual magnetism. A hook, S, is provided in order to retain the lever in its position when no current is passing through the apparatus. On the opposite end of the lever a weight, J is suspended, and from the weight a string passes overpulleys to the wheel U, which is keyed onto the spindle of the stopvalve of the motor in such a manner that the weight, when free, in falling closes the valve.

The apparatus works in the following manner: When the current passes through the electro-magnet O, the armature Q is attracted so that the hook S, which is not further wanted, becomes disengaged. If any interruption now occurs in the circuitthe magnetism ceases instantly, the consequence of which is that the weight J depresses the shorter end of the le ver Q and glides oft, thus stopping the motor. If this apparatus did not exist the dynamomachine and the motor would, in the event of an interruption in the circuit, increase their rapidity in consequence of motive power being no longer transformed into electricity,a-nd owing to the great speed the machine might be damaged.

Another danger for the dynamo-machine may arise in the event of short-circuiting a portion of the main circuit. In such an event the resistance diminishes and the power of the cun'entincreases, so that the insulation of the machine and the circuit may be destroyed. \Vhen with this arrangement shortcircuiting has taken place, and consequently the current has increased, the attractive power of the magnet D will likewise be increased, and the armature O is attracted and moves to its magnet, allowing the bar K, with its vessel of mercury I, to fall down and disconnect the strips F and G. The elcctro-magnet G then loses its magnetism and the weight J falls down and stops the motor.

I claim Automatic stop apparatus for motors driving dynamo-machines, consisting of two electro-magnets, O and D, in the main circuit, acting each upon its lever-armature, in combination with a string and weight, J, strips F and G, and movable vessel I, which contains mercury and is controlled by one of the electro-' magnets, the said stop apparatus eli'ecting in an automatic manner the stopping of the motor driving the dynamo-machine in the event of interruption of the circuit or short-circuiting, substantially as described.

oscnn FREDRIK JONSSON.

\Vitnesses:

NERE A. ELFWING, ERNST SYANQVIST. 

